I'm trying to install the new patch for the game but after about 80% of the installation is complete the installer locks up.
The pathc_log.txt file says that the crash is because I have "the Incorrect version" of the map files and a couple of other files but I don't understand why this happens, I even uninstalled the game completely and downloaded the entire game installer from GOG again and I still get the same error from the patch. Hope someone can help me with this as I'm really looking forward to playing the game.

try downloading the patch again

I tried that too, several times even.

Well, now it decided to work all of a sudden. I don't know why it didn't work before when I did everything the exact same way, but at least the problem is solved. The game still lags like crazy though.